In the prior art, a number of devices for attenuation are taught for use with conventional coaxial and flat strip transmission lines. One such device is described in U.S. Pat. No. 3,157,846 of B. O. Weinschel. The attenuator of the type disclosed in U.S. Pat. No. 3,740,676 of V. E. Garuts, a co-inventor of the present invention, has a greater high frequency response then that taught in U.S. Pat. No. 3,157,846 but is limited in that a lossy distortionless transmission line forming such attenuator has a constant input impedance equal to its characteristic impedance and a constant output impedance equal to one-half of its characteristic impedance.
Another disadvantage of such attenuation devices is that although most can replace any potentiometer, they are of restricted usefulness when employed, say, in the vertical amplifier of a cathode ray oscilloscope having a wide band frequency response from DC to several hundred megahertz.